A plant-enriched diet for a healthy mind (and a longer life!)

AUTHOR: Dr Philippa Jackson

A study published last month revealed that adopting a diet high in whole grains, legumes, nuts, fruits, vegetables and fish and low in red and processed meat and sugary beverages could lead to an increased lifespan [1]. The authors revealed that the greatest gains in life expectancy could be possible by changing to an optimal diet in your 20’s (10 years), but even changes later in life at the age of 80 might extend life by almost three-and-a-half-years.

When considering ‘optimal ageing’, thoughts may immediately turn to a long life free of chronic illness, especially non-communicable diseases such as cardiovascular disease, cancer and diabetes, and this study suggests that plant-based nutrient-dense foods are fundamental to ageing successfully. Of course, ensuring optimal mental health and brain function across the lifespan is equally important and here nutrition also has an important role to play. Indeed, a recent review found that dietary patterns containing the exact same beneficial food groups identified in the study above had a protective effect with regards to improving measures of cognitive impairment and/or reducing risk of cognitive impairment or dementia [2].

However, you don’t need to wait until older adulthood to feel the benefits of following a healthy diet; data from our lab at Nothumbria University collected over the last two decades has revealed beneficial effects of a wide variety of nutrients (e.g. vitamins, omega-3 fatty acids), herbal extracts (e.g. ginkgo biloba, ginseng, lemon balm) and plant compounds found in everyday products (tea, chocolate, berry fruits) on cognitive function and mood in healthy adults that are observable after the course of anything from a few minutes to a few weeks, depending on the item. In this blog, I’ve talked about some of our more recent findings.

There’s more than just caffeine to your morning coffee ‘hit’

The alerting effects of coffee are often ascribed to the beverage’s caffeine content. Although not untrue, caffeine is not the only ‘active’ ingredient in coffee; in fact, the coffee bean itself contains a plethora of different compounds that have the potential to either directly affect brain function or work together with caffeine to produce effects. The major group of compounds of interest in coffee are called chlorogenic acids (CGA) and are particularly enriched in the flesh of the coffee fruit itself (coffee berry) and green unroasted beans.

Although roasting the beans diminishes the amount of CGA found in your average cup of coffee they are still present, with one study reporting CGA espresso content in several European countries in the range of 6–188 mg per cup [3]. Two recent studies from our lab investigated the effects of coffee berry extract on mood and cognitive performance and found a consistent pattern of alerting effects that was evident across the entire six-hour testing period, which cannot be attributed to the relatively small amount of caffeine found in the extract (22 mg vs 75 mg in an average cup of coffee) [4, 5].

These results support some of our previous findings, which demonstrated alerting effects of decaffeinated coffee in both younger and older adults [6]. Collectively, these data point to an alerting effect of the non-caffeine components of coffee. As it is these compounds that are also likely to underpin coffee’s beneficial effects on physical health [7], individuals choosing decaffeinated options are still getting a healthful ‘hit’ in the morning too.

The world’s most valuable spice: An unlikely mood enhancer

Saffron is known throughout the world for its distinctive colour and taste and has been used in culinary dishes across Europe and Asia for millennia. Saffron stigmas are naturally rich in several bioactive compounds and its pain-relieving and sedative properties are recognised by traditional Asian medicine where it is used to treat a range of physical ailments including menstrual disorder, inflammation and depression [8, 9].

The anti-depressant activity of this herb has recently been explored in controlled trials; a meta-analysis of these data revealed that 30 g/d saffron extract for six weeks significantly improved symptoms in patients with major depressive disorder compared to placebo, but also had similar antidepressant efficacy when compared with mainstream antidepressant medications [10].

Our lab investigated whether these mood effects could be seen in otherwise healthy adults who reported subclinical feelings of low mood and anxiety and/or stress, who would not meet a formal diagnosis of depression. Compared to placebo, we found that eight weeks’ supplementation with 30 g/d saffron extract improved depressive symptoms, although no effects were observed for stress or anxiety [11]. Findings such as this are important as they highlight the potential for non-pharmacological plant extracts in supporting mental health. 

A humble herb with an ancient medicinal past

Few would naturally think of their herb garden as a source of the next generation of dementia preventing products but the aromatic herbs belonging to the mint family such as peppermint, rosemary, lavender, lemon balm and sage are a rich source of phytochemicals with established psychoactive properties relevant to cognitive decline. Of all these culinary herbs, sage has the widest documented use in traditional medicine dating back to the ancient Greeks and is reputed to have cognitive or memory enhancing effects by several medicinal systems [12].

These effects were investigated by our lab using controlled trials and we have demonstrated consistent improvements in cognitive function in healthy adults following single doses of two different species of sage, Salvia officinalis (garden sage) and Salvia lavandulaefolia (Spanish sage)[13, 14]. Concurrent beneficial effects on mood such as increased calmness and alertness [15] and reduced mental fatigue [16] have also been observed.

Our lab also recently demonstrated beneficial effects on working, or short term, memory performance after four weeks’ daily consumption of a treatment combining both these sage species [17], opening up the exciting possibility of exploiting the individual chemical profiles of both species for maximum benefit.

So what should we be eating?

These are just a few examples of some of the interesting effects of different dietary items, some of which are consumed every day. The plants we ingest, in whatever form, are packed with compounds that interact with the chemistry of our bodies and brains that have the potential to help us live healthier, happier, and ultimately longer lives. The best way to achieve this is to incorporate as wide a variety of plants into your diet as you can.

About the Author

Dr Philippa Jackson is an associate professor in the psychology department at northumbria university and associate director of our Brain, Performance and Nutrition Research Centre. The centre sits within our Health and Wellbeing Research Group.

References

1. Fadnes, L.T., et al., Estimating impact of food choices on life expectancy: A modeling study. PLOS Medicine, 2022. 19(2): p. e1003889.
2. Boushey, C., et al., USDA Nutrition Evidence Systematic Reviews, in Dietary Patterns and Neurocognitive Health: A Systematic Review. 2020, USDA Nutrition Evidence Systematic Review: Alexandria (VA).
3. Ludwig, I.A., et al., Variations in caffeine and chlorogenic acid contents of coffees: what are we drinking? Food Funct, 2014. 5(8): p. 1718-26.
4. Jackson, P.A., et al., A Randomized, Crossover Study of the Acute Cognitive and Cerebral Blood Flow Effects of Phenolic, Nitrate and Botanical Beverages in Young, Healthy Humans. Nutrients, 2020. 12(8): p. 2254.
5. Jackson, P.A., et al., Acute cognitive performance and mood effects of coffee berry and apple extracts: A randomised, double blind, placebo controlled crossover study in healthy humans. Nutr Neurosci, 2021: p. 1-9.
6. Haskell-Ramsay, C.F., et al., The Acute Effects of Caffeinated Black Coffee on Cognition and Mood in Healthy Young and Older Adults. Nutrients, 2018. 10: p. 1386.
7. Tajik, N., et al., The potential effects of chlorogenic acid, the main phenolic components in coffee, on health: a comprehensive review of the literature. Eur J Nutr, 2017. 56(7): p. 2215-2244.
8. Rios, J.L., et al., An update review of saffron and its active constituents. Phytotherapy Research, 1996. 10(3): p. 189-193.
9. Akhondzadeh, S., et al., Crocus sativus L. in the treatment of mild to moderate depression: a double-blind, randomized and placebo-controlled trial. Phytother Res, 2005. 19(2): p. 148-51.
10. Hausenblas, H.A., et al., Saffron (Crocus sativus L.) and major depressive disorder: a meta-analysis of randomized clinical trials. J Integr Med, 2013. 11(6): p. 377-83.
11. Jackson, P. A., Forster, J., Khan, J., Pouchieu, C., Dubreuil, S., Gaudout, D., … & Kennedy, D. O. (2021). Effects of saffron extract supplementation on mood, well-being, and response to a psychosocial stressor in healthy adults: A randomized, double-blind, parallel group, clinical trial. Frontiers in nutrition, 365.
12. Kennedy, D.O. and A.B. Scholey, The psychopharmacology of European herbs with cognition-enhancing properties. Curr Pharm Des, 2006. 12(35): p. 4613-23.
13. Kennedy, D.O., et al., Monoterpenoid extract of sage (Salvia lavandulaefolia) with cholinesterase inhibiting properties improves cognitive performance and mood in healthy adults. J Psychopharmacol, 2011. 25(8): p. 1088-100.
14. Kennedy, D.O., et al., Effects of cholinesterase inhibiting sage (Salvia officinalis) on mood, anxiety and performance on a psychological stressor battery. Neuropsychopharmacology, 2006. 31(4): p. 845-852.
15. Tildesley, N.T., et al., Salvia lavandulaefolia (Spanish sage) enhances memory in healthy young volunteers. Pharmacol Biochem Behav, 2003. 75(3): p. 669-74.
16. Tildesley, N.T., et al., Positive modulation of mood and cognitive performance following administration of acute doses of Salvia lavandulaefolia essential oil to healthy young volunteers. Physiol Behav, 2005. 83(5): p. 699-709.
17. Wightman, E.L., et al., The Acute and Chronic Cognitive Effects of a Sage Extract: A Randomized, Placebo Controlled Study in Healthy Humans. Nutrients, 2021. 13(1): p. 218.